1. Field of the Invention
This invention relates to methods and devices for harvesting plants having differing heights and stem lengths to yield a harvested crop wherein each stem is severed at a uniform, predetermined length from the top of the plant. More particularly the present invention discloses a method and device for harvesting onion seed umbels to yield a umbel and attached stem of common length.
2. Prior Art
Although many years of mechanized farming has generated a substantial number of inventions for automating many areas of manual labor, there have remained several specific areas of agriculture technology which continue to require intense manual labor. One such area involves the harvesting of onion seed.
The onion seed crop is unique in several aspects. In addition to the fact that the growth cycle for the mature umbel or seed cluster is two years, specific harvesting requirements must be satisfied to ensure that the two year growth results in a sellable commodity. Specifically, the seed cluster or umbel forms atop a long stem whose length from root to cluster varies substantially. This seed cluster must be harvested several weeks prior to final maturity of the onion seeds. In order to ensure final maturation, the seed cluster or umbel is severed from the remaining plant with an attached stem length of approximately 4 inches. This severed plant is then subjected to a controlled drying environment. The attached segment of stem provides a moisture supply to complete the maturation of the onion seeds and ensure a sellable product within conventional marketing limitations.
Because each stem is of a different length conventional harvesting devices are not effective in onion seed agriculture. To apply such devices typically results in a cut of the stem at a uniform distance above the ground level, resulting in severed stem lengths at a variety of distances. Where such stem lengths are less than 4 inches, insufficient moisture will be supplied to the seeds. Stem length in excess of 4 inches results in poor seed quality because of increased moisture. The costly nature of such mistakes is readily apparent to the farmer who spends two years of cultivation and care to generate a final onion seed umbel which was ready for harvest.
As a consequence, conventional current commercial methods for harvesting onion seed rely on migrant workers who individually cut each stem at the appropriate 4 inch distance from the umbel, and place the umbel and stem in a harvest bin. Because the harvest must be accomplished within a very short time frame, the farmer is at the mercy of unpredictable work habits and ethics which can jeopardize two years of agricultural effort in generating the final crop. These unique circumstances combine to challenge the most careful planning of the onion seed farmer who must deal with these critical harvesting factors which are often beyond the farmer's control.